U.S. patent application number 11/334471 was filed with the patent office on 2006-07-20 for silicone-sealed led.
This patent application is currently assigned to Shin-Etsu Chemical Co., Ltd.. Invention is credited to Kei Miyoshi, Eiichi Tabei.
Application Number | 20060159937 11/334471 |
Document ID | / |
Family ID | 36177964 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060159937 |
Kind Code |
A1 |
Miyoshi; Kei ; et
al. |
July 20, 2006 |
Silicone-sealed LED
Abstract
Provided is a silicone-sealed LED including: a LED chip, a cured
silicone rubber layer which coats the LED chip, and a cured
silicone resin layer which coats and seals the periphery of the
cured silicone rubber layer. Also provided are a process for
producing the silicone-sealed LED and a process for sealing a LED.
In the silicone-sealed LED, a silicone rubber layer disposed
between a silicone resin layer that represents the sealing body and
a LED chip functions as a buffer layer, meaning cracks are not
easily generated in the silicone resin layer that represents the
sealing body, while full use is made of the excellent heat
resistance, weather resistance, and color fastness of the silicone
rubber and the silicone resin.
Inventors: |
Miyoshi; Kei; (Annaka-shi,
JP) ; Tabei; Eiichi; (Annaka-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Shin-Etsu Chemical Co.,
Ltd.
Chiyoda-ku
JP
|
Family ID: |
36177964 |
Appl. No.: |
11/334471 |
Filed: |
January 19, 2006 |
Current U.S.
Class: |
428/447 ;
257/E33.059; 438/127; 524/862; 525/477 |
Current CPC
Class: |
C08L 83/04 20130101;
C08G 77/16 20130101; C08L 83/00 20130101; C08G 77/12 20130101; C08L
83/04 20130101; Y10T 428/31663 20150401; C08G 77/20 20130101; C08G
77/18 20130101; H01L 33/56 20130101 |
Class at
Publication: |
428/447 ;
438/127; 524/862; 525/477 |
International
Class: |
B32B 27/00 20060101
B32B027/00; H01L 21/56 20060101 H01L021/56 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2005 |
JP |
2005-012510 |
Claims
1. A silicone-sealed LED comprising: a LED chip, a cured silicone
rubber layer which coats said LED chip, and a cured silicone resin
layer which coats and seals a periphery of said cured silicone
rubber layer.
2. The silicone-sealed LED according to claim 1, wherein said cured
silicone rubber layer is a cured product of a liquid curable
silicone rubber composition, and said cured silicone resin layer is
a cured product of a liquid curable silicone resin composition.
3. The silicone-sealed LED according to claim 2, wherein said
liquid curable silicone rubber composition and said liquid curable
silicone resin composition are both addition curing-type
compositions that are cured by a hydrosilylation reaction between
silicon atom-bonded alkenyl groups and silicon atom-bonded hydrogen
atoms.
4. The silicone-sealed LED according to claim 3, wherein within
said liquid addition curing-type silicone rubber composition, a
quantity of silicon atom-bonded hydrogen atoms relative to each 1
mol of silicon atom-bonded alkenyl groups is no greater than 0.9
mols, and within said liquid addition curing-type silicone resin
composition, a quantity of silicon atom-bonded hydrogen atoms
relative to each 1 mol of silicon atom-bonded alkenyl groups
exceeds 0.9 mols.
5. The silicone-sealed LED according to claim 1, wherein a hardness
of said cured silicone rubber layer, as measured by a JIS Type A
hardness meter, is no greater than 50, and a hardness of said cured
silicone resin layer, as measured by a Shore D hardness meter, is
at least 30.
6. The silicone-sealed LED according to claim 2, wherein a
difference between a refractive index of said liquid curable
silicone rubber composition and a refractive index of said liquid
curable silicone resin composition is no greater than 0.05.
7. The silicone-sealed LED according to claim 2, wherein said
liquid curable silicone rubber composition comprises: (A1) an
organopolysiloxane containing at least one silicon atom-bonded
alkenyl group within each molecule, and represented by a formula
(1) shown below: R.sub.3SiO(SiR.sub.2O).sub.aSiR.sub.3 (1)
(wherein, each R represents, independently, an unsubstituted or
substituted monovalent hydrocarbon group, and a represents a
positive number at which the viscosity of said organopolysiloxane
at 23.degree. C. is no greater than 100,000 mPas), (B1) an
organohydrogenpolysiloxane containing at least two silicon
atom-bonded hydrogen atoms within each molecule, and represented by
a formula (2) shown below:
R.sup.1.sub.3SiO(SiR.sup.2.sub.2O).sub.b(SiR.sup.2(H)O).sub.cSiR.sup.1.su-
b.3 (2) (wherein, each R.sup.1 represents, independently, a
hydrogen atom or an unsubstituted or substituted monovalent
hydrocarbon group that contains no aliphatic unsaturated bonds,
each R.sup.2 represents, independently, an unsubstituted or
substituted monovalent hydrocarbon group that contains no aliphatic
unsaturated bonds, and b and c represent positive numbers at which
the viscosity of said organohydrogenpolysiloxane at 23.degree. C.
is no greater than 10,000 mPas), in a quantity that ensures that a
quantity of silicon atom-bonded hydrogen atoms within said silicone
rubber relative to each 1 mol of silicon atom-bonded alkenyl groups
within said silicone rubber is no greater than 0.9 mols, and (C) an
effective quantity of a hydrosilylation reaction catalyst.
8. The silicone-sealed LED according to claim 2, wherein said
liquid curable silicone resin composition comprises: (A2) an
organopolysiloxane with a viscosity of at least 10 mPas at
23.degree. C., represented by an average composition formula (3)
shown below: R.sup.3.sub.dSiO.sub.(4-d)/2 (3) (wherein, each
R.sup.3 represents, independently, an unsubstituted or substituted
monovalent hydrocarbon group or alkoxy group, or a hydroxyl group,
provided 5 to 50 mol % of all R.sup.3 groups represent alkenyl
groups, and d represents a number that satisfies
1.ltoreq.d.ltoreq.2), (B2) an organohydrogenpolysiloxane with a
viscosity no greater than 1,000 mPas at 23.degree. C., and
containing at least two silicon atom-bonded hydrogen atoms within
each molecule, represented by an average composition formula (4)
below: R.sup.4.sub.eH.sub.fSiO.sub.(4-e-f)/2 (4) (wherein, each
R.sup.4 represents, independently, an unsubstituted or substituted
monovalent hydrocarbon group that contains no aliphatic unsaturated
bonds, e represents a number from 0.7 to 2.1, f represents a number
from 0.01 to 1.0, and e+f satisfies a range from 0.8 to 3), and (C)
an effective quantity of a hydrosilylation reaction catalyst.
9. The silicone-sealed LED according to claim 2, wherein said
liquid curable silicone resin composition comprises: (A3) a
siloxane-based compound that contains at least two silicon
atom-bonded alkenyl groups within each molecule, (B3) a
siloxane-polycyclic hydrocarbon-based compound, which is an
addition reaction product of (a) a siloxane-based compound
containing at least three silicon atom-bonded hydrogen atoms within
each molecule, and (b) a polycyclic hydrocarbon containing two
addition reactive carbon-carbon double bonds within each molecule,
and contains at least two silicon atom-bonded hydrogen atoms within
each molecule, and (C) a hydrosilylation reaction catalyst.
10. A process for producing a silicone-sealed LED, comprising the
steps of: (1) coating a LED chip with a cured silicone rubber
layer, and (2) coating and sealing a periphery of said cured
silicone rubber layer with a cured silicone resin layer.
11. The process according to claim 10, wherein said cured silicone
rubber layer is a cured product of a liquid curable silicone rubber
composition, and said cured silicone resin layer is a cured product
of a liquid curable silicone resin composition.
12. The process according to claim 11, wherein said step (1)
comprises the steps of: applying said liquid curable silicone
rubber composition to said LED chip and curing said liquid curable
silicone rubber composition to form said cured silicone rubber
layer on said LED chip, and said step (2) comprises the steps of:
applying said liquid curable silicone resin composition to the
periphery of said cured silicone rubber layer and curing said
liquid curable silicone resin composition to form said cured
silicone resin layer on the periphery of said cured silicone rubber
layer.
13. A process for sealing a LED, comprising the steps of: (3)
coating a LED chip with a cured silicone rubber layer, and (4)
coating and sealing a periphery of said cured silicone rubber layer
with a cured silicone resin layer.
14. The process according to claim 13, wherein said cured silicone
rubber layer is a cured product of a liquid curable silicone rubber
composition, and said cured silicone resin layer is a cured product
of a liquid curable silicone resin composition.
15. The process according to claim 13, wherein said step (3)
comprises the steps of: applying said liquid curable silicone
rubber composition to said LED chip and curing said liquid curable
silicone rubber composition to form said cured silicone rubber
layer on said LED chip, and said step (4) comprises the steps of:
applying said liquid curable silicone resin composition to the
periphery of said cured silicone rubber layer and curing said
liquid curable silicone resin composition to form said cured
silicone resin layer on the periphery of said cured silicone rubber
layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a silicone-sealed LED using
a silicone resin as a sealing material, and in particular, relates
to a silicone-sealed LED provided with a buffer layer comprising
silicone rubber between the silicone resin seal and the LED chip.
The present invention also relates to a process for producing the
silicone-sealed LED and a process for sealing a LED.
[0003] 2. Description of the Prior Art
[0004] Epoxy resins are generally used as the sealing materials for
light emitting diode elements. However, because epoxy resins have a
high modulus of elasticity, the resulting distortions which occur
during temperature cycling due to the different coefficients of
linear expansion for the wire, the chip, and the epoxy resin mean
stress acts on the wire bonding, and as a result, cracks can occur
in the sealing body comprising the resin, disconnecting the wire
bonding. Consequently, as a result of the stress applied by the
epoxy resin seal body to the LED chip, there is a danger of the
crystal structure of the LED chip being destroyed, decreasing the
luminous efficiency of the LED.
[0005] As a countermeasure to these problems, a method using a
rubber-like silicone RTV as a buffer material, wherein the exterior
thereof is sealed with an epoxy resin, is now established as an
accepted method. However, with this method, because the epoxy resin
does not adhere to the silicone resin, interfacial peeling occurs
on temperature cycling, considerably decreasing the light
extraction efficiency over time.
[0006] On the other hand, sealing using silicone resins instead of
epoxy resins has also been proposed as a method of resolving the
aforementioned problems (patent references 1 to 3). Because
silicone resins exhibit superior heat resistance, weather
resistance and color fastness and the like when compared with epoxy
resins, in recent years, examples using silicone resins, primarily
with blue and white LEDs, have become prevalent. However, although
silicone resins have a low modulus of elasticity compared to epoxy
resins, the mechanical properties such as the flexural strength are
inferior, leaving the problem of a tendency for cracks to
occur.
[0007] [Patent Reference 1] JP 11-1619A
[0008] [Patent Reference 2] US 2002/0161140 A1
[0009] [Patent Reference 3] US 2004/0116640 A1
SUMMARY OF THE INVENTION
[0010] The present invention provides a silicone-sealed LED in
which cracks are not easily generated in the silicone resin layer
that represents the sealing body, while full use is made of the
excellent heat resistance, weather resistance, and color fastness
of the silicone rubber and the silicone resin. Another object of
the present invention is to provide a process for producing the
silicone-sealed LED and a process for sealing a LED.
[0011] As a result of intensive investigation aimed at achieving
the above object, the inventors of the present invention completed
the present invention. In other words, the present invention
provides a silicone-sealed LED which comprises:
[0012] a LED chip,
[0013] a cured silicone rubber layer which coats the LED chip,
and
[0014] a cured silicone resin layer which coats and seals the
periphery of the cured silicone rubber layer. The present invention
also provides a process for producing the silicone-sealed LED and a
process for sealing a LED.
[0015] The silicone rubber layer, which exists between the silicone
resin layer that represents the sealing body and the LED chip, acts
as a buffer layer, and consequently a silicone-sealed LED of the
present invention is resistant to cracking of the silicone resin
layer of the sealing body, while still exhibiting the excellent
heat resistance, weather resistance and color fastness of
silicone.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] As follows is a more detailed description of the present
invention.
[0017] As described above, a silicone resin-sealed LED of the
present invention comprises a LED chip, a cured silicone rubber
layer which coats the same, and a cured silicone resin layer which
coats and seals the periphery of the cured silicone rubber
layer.
[0018] From the viewpoint of alleviating the stress within the
produced silicone-sealed LED, the hardness of the cured silicone
rubber layer, as measured by a JIS Type A hardness meter, is
preferably no greater than 50, even more preferably no greater than
30, and most preferably from 0 to 20, and the hardness of the cured
silicone resin layer, as measured by a Shore D hardness meter, is
preferably at least 30, more preferably at least 40, and most
preferably from 60 to 90.
[0019] Since it is preferable for the reflection of light at the
interface between the cured silicone rubber layer and the cured
silicone resin layer to be prevented, the difference between the
refractive index of the liquid curable silicone rubber composition
and the refractive index of the liquid curable silicone resin
composition is preferably no greater than 0.05, more preferably no
greater than 0.03, and most preferably no greater than 0.025.
[0020] The cured silicone rubber layer and the cured silicone resin
layer can be formed, for example, by curing a liquid curable
silicone rubber composition and a liquid curable silicone resin
composition, respectively.
[0021] Examples of the liquid curable silicone rubber composition
and the liquid curable silicone resin composition include
conventional addition curing-type and condensation curing-type
liquid curable compositions. However, addition curing-type
compositions in which the curing reaction can proceed as rapidly as
possible, where it is unnecessary to remove the alcohols and the
like that represent the by-products of the curing reaction, and in
which the reaction progresses quantitatively, are preferred, and of
such compositions, those that are room temperature curable or heat
curable are preferred.
[0022] Liquid curable silicone rubber compositions and liquid
curable silicone resin compositions that are the preferred addition
curing-type compositions described above typically comprise a
compound which contains silicon atom-bonded alkenyl groups within
the molecule, a compound which contains silicon atom-bonded
hydrogen atoms within the molecule, and a hydrosilylation reaction
catalyst, and are cured by a hydrosilylation reaction between the
silicon atom-bonded alkenyl groups and the silicon atom-bonded
hydrogen atoms. However, in terms of achieving favorable adhesion
between the cured silicone rubber layer and the cured silicone
resin layer, it is preferable that the quantity of silicon
atom-bonded hydrogen atoms relative to each 1 mol of silicon
atom-bonded alkenyl groups within the addition curing-type liquid
silicone rubber composition is no greater than 0.9 mols, and even
more preferably from 0.5 to 0.9 mols, and most preferably from 0.6
to 0.8 mols, and it is preferable that the quantity of silicon
atom-bonded hydrogen atoms relative to each 1 mol of silicon
atom-bonded alkenyl groups in the addition curing-type liquid
silicone resin composition exceeds 0.9 mols, and is even more
preferably from 0.91 to 4.0 mols, and most preferably from 0.95 to
2.0 mols.
[0023] As follows, the addition curing-type silicone rubber
composition and the addition curing-type silicone resin composition
are explained in sequence.
[0024] <Addition Curing-Type Liquid Curable Silicone Rubber
Composition>
[0025] Examples of suitable addition curing-type liquid curable
silicone rubber compositions include the following
compositions.
[0026] A composition comprising:
(A1) an organopolysiloxane containing at least one silicon
atom-bonded alkenyl group within each molecule, and represented by
a formula (1) shown below: R.sub.3SiO(SiR.sub.2O).sub.aSiR.sub.3
(1) (wherein, each R represents, independently, an unsubstituted or
substituted monovalent hydrocarbon group, and a represents a
positive number at which the viscosity of the organopolysiloxane at
23.degree. C. is no greater than 100,000 mPas), (B1) an
organohydrogenpolysiloxane containing at least two silicon
atom-bonded hydrogen atoms within each molecule, and represented by
a formula (2) shown below, in a quantity that ensures that the
quantity of silicon atom-bonded hydrogen atoms within the silicone
rubber composition relative to each 1 mol of silicon atom-bonded
alkenyl groups in the silicone rubber composition is no greater
than 0.9 mols,
R.sup.1.sub.3SiO(SiR.sup.2.sub.2O).sub.b(SiR.sup.2(H)O).sub.cSiR.sup.1.su-
b.3 (2) (wherein, each R.sup.1 represents, independently, a
hydrogen atom or an unsubstituted or substituted monovalent
hydrocarbon group that contains no aliphatic unsaturated bonds,
each R.sup.2 represents, independently, an unsubstituted or
substituted monovalent hydrocarbon group that contains no aliphatic
unsaturated bonds, and b and c represent positive numbers at which
the viscosity of the organohydrogenpolysiloxane at 23.degree. C. is
no greater than 10,000 mPas), and (C) an effective quantity of a
hydrosilylation reaction catalyst.
[0027] (A1) Organopolysiloxane
[0028] As described above, the organopolysiloxane that represents
the component (A1) is represented by the formula (1) above,
although it is not preferable from the aspect of workability for it
to become highly viscous, and the viscosity at 23.degree. C. is
typically no greater than 100,000 mPas, preferably no greater than
30,000 mPas, and is most preferably from 60 to 10,000 mPas. This
organopolysiloxane must contain at least one silicon atom-bonded
alkenyl group within each molecule, and preferably contains from 2
to 20, and most preferably from 2 to 10 of such alkenyl groups.
Within the organopolysiloxane molecule, these silicon atom-bonded
alkenyl groups may be found at the molecular chain terminals, at
non-terminal molecular chain positions, or at both of these
positions.
[0029] In the formula (1) above, a represents a positive number
that ensures that the viscosity of the organopolysiloxane satisfies
the above range.
[0030] The number of carbon atoms within the unsubstituted or
substituted monovalent hydrocarbon group represented by R is
typically from 1 to 12, and is preferably from 1 to 8. Examples of
this monovalent hydrocarbon group include alkyl groups such as a
methyl group, ethyl group, n-propyl group, isopropyl group, butyl
group, isobutyl group, tert-butyl group, hexyl group, cyclohexyl
group, octyl group, norbornyl group, or isonorbornyl group; alkenyl
groups such as a vinyl group, allyl group, propenyl group, or
butenyl group; aryl groups such as a phenyl group or tolyl group;
aralkyl groups such as a benzyl group or phenylethyl group; and
substituted hydrocarbon groups such as a trifluoropropyl group in
which a portion of, or all of, the hydrogen atoms of these groups
have been substituted with a halogen atom such as fluorine or
chlorine.
[0031] The structure of the organopolysiloxane of this component is
not particularly restricted from the aspect of stress relaxation,
and suitable examples include a straight-chain, branched-chain,
three-dimensional network, or cyclic structure, although it is
desirable that the structure does not greatly differ from the
structure of the organopolysiloxane in the cured silicone resin
layer, which coats and seals the periphery of the cured silicone
rubber layer generated by this component. The reason for this
requirement is to prevent the reflection of light at the interface
between the cured silicone rubber layer and the cured silicone
resin layer within the silicone-sealed LED.
[0032] Examples of the organopolysiloxane of this component include
ViMe.sub.2SiO(SiMe.sub.2O).sub.gSiMe.sub.2Vi,
ViMe.sub.2SiO(SiMe.sub.2O).sub.g(SiMePhO).sub.hSiMe.sub.2Vi,
ViMe.sub.2SiO(SiMe.sub.2O).sub.g(SiPh.sub.2O)hSiMe.sub.2Vi,
ViMe.sub.2SiO(SiMe(C.sub.3H.sub.4F.sub.3)O).sub.gSiMe.sub.2Vi,
Me.sub.3SiO(SiViMeO).sub.g(SiMe.sub.2O).sub.hSiMe.sub.3,
ViMe.sub.2SiO(SiViMeO).sub.g(SiMe.sub.2O)hSiMe.sub.2Vi,
Vi.sub.3SiO(SiMe.sub.2O).sub.gSiMeVi.sub.3, and
ViMe.sub.2SiO(SiMe.sub.2O).sub.gSiMe.sub.3.
[0033] (wherein, Vi represents a vinyl group, Me represents a
methyl group, Ph represents a phenyl group, g and h each
independently represent positive integers, and g+h falls within a
range that satisfies the viscosity defined above. These definitions
also apply below.)
[0034] The organopolysiloxane of this component may use either a
single compound, or a combination of two or more different
compounds.
[0035] (B1) Organohydrogenpolysiloxane
[0036] The organohydrogenpolysiloxane that represents the component
(B1) acts as a cross-linking agent for curing the composition via a
cross-linking reaction with the component (A1), and is represented
by the formula (2) shown above.
[0037] The viscosity of this organohydrogenpolysiloxane at
23.degree. C. is no greater than 10,000 mPas, and from the aspects
of workability and ease of production of the silicone rubber
composition, is preferably no greater than 5,000 mPas, and is most
preferably within a range from 1 to 3,000 mPas. This
organohydrogenpolysiloxane must contain at least two silicon
atom-bonded hydrogen atoms within each molecule, and preferably
contains from 2 to 100, and most preferably from 3 to 50 of such
hydrogen atoms. In the organohydrogenpolysiloxane molecule, these
silicon atom-bonded hydrogen atoms may be found at the molecular
chain terminals or at non-terminal molecular chain positions, or at
both of these positions.
[0038] There are no particular restrictions on the structure of the
organohydrogenpolysiloxane of this composition, and suitable
examples include a straight-chain, branched-chain,
three-dimensional network, or cyclic structure.
[0039] This composition is preferably able to be mixed uniformly
with the component (A1), and furthermore, in order to ensure that
the resulting silicone resin-sealed LED exhibits excellent optical
characteristics, a composition which is as close as possible to
colorless or transparent is preferable.
[0040] In the formula (2) above, b and c represent positive numbers
that ensure that the viscosity of the organopolysiloxane satisfies
the above range.
[0041] The number of carbon atoms within the unsubstituted or
substituted monovalent hydrocarbon group represented by R.sup.1,
which contains no aliphatic unsaturated bonds, is typically from 1
to 10, and is preferably from 1 to 8. Examples of this monovalent
hydrocarbon group include alkyl groups such as a methyl group,
ethyl group, n-propyl group, isopropyl group, butyl group, isobutyl
group, tert-butyl group, hexyl group, cyclohexyl group, or octyl
group; aryl groups such as a phenyl group or tolyl group; aralkyl
groups such as a benzyl group; and halogen-substituted monovalent
hydrocarbon groups in which either a portion of, or all of, the
hydrogen atoms within these groups have been substituted with a
halogen atom such as fluorine or chlorine, including a chloromethyl
group, bromoethyl group, or trifluoropropyl group. R.sup.1 is
preferably a hydrogen atom, methyl group, phenyl group or
trifluoropropyl group.
[0042] The number of carbon atoms within the unsubstituted or
substituted monovalent hydrocarbon group represented by R.sup.2,
which contains no aliphatic unsaturated bonds, is typically from 1
to 10, and is from preferably 1 to 6. Examples of this monovalent
hydrocarbon group include the unsubstituted and substituted
monovalent hydrocarbon groups listed above for R.sup.1.
[0043] Examples of the organohydrogenpolysiloxane of this component
include Me.sub.3SiO(SiMe(H)O).sub.iSiMe.sub.3,
Me.sub.3SiO(SiMe(H)O).sub.i(SiMe.sub.2O).sub.j SiMe.sub.3,
Me.sub.3SiO(SiMe(H)O).sub.i(SiPh.sub.2O).sub.k(SiMe.sub.2O).sub.jSiMe.sub-
.3, (H)Me.sub.2SiO(SiMe.sub.2O).sub.jSiMe.sub.2(H),
(H)Me.sub.2SiO(SiMe(H)O).sub.i(SiMe.sub.2O).sub.j
SiMe.sub.2(H),
[0044] (wherein, i, j and k each independently represent positive
integers, and i, i+j, and i+j+k each fall within a range that
satisfies the viscosity defined above), cyclic compounds such as
tetramethyltetrahydrocyclosiloxane, compounds in which a portion of
the hydrogen atoms within these compounds have been reacted with
vinyltrimethoxysilane or an epoxy compound that contains an
unsaturated bond, and PhSi(OSiMe.sub.2H).sub.3.
[0045] As described below, this silicone rubber composition may
also include components containing silicon atom-bonded alkenyl
groups other than the component (A1), and/or components containing
silicon atom-bonded hydrogen atoms other than the component (B1).
Accordingly, the quantity of silicon atom-bonded hydrogen atoms in
this silicone rubber composition relative to each 1 mol of silicon
atom-bonded alkenyl groups in this silicone rubber composition is
typically within a range from 0.5 to 5 mols, and preferably within
a range from 0.6 to 3 mols, and the proportion of the total number
of silicon atom-bonded hydrogen atoms in this silicone rubber
composition accounted for by the silicon atom-bonded hydrogen atoms
within the component (B1) is typically within a range from 1 to 100
mol %, and is preferably from 2 to 100 mol %. Moreover, the
proportion of the total number of silicon atom-bonded alkenyl
groups in this silicone rubber composition accounted for by the
silicon atom-bonded alkenyl groups in the component (A1) is
typically within a range from 10 to 100 mol %, and is preferably
from 30 to 100 mol %. With such values, a cured rubber with
excellent physical properties, such as mechanical strength, can be
obtained.
[0046] Furthermore, as mentioned above, from the viewpoint of
improving the adhesion between the cured silicone rubber layer and
the cured silicone resin layer, it is preferable that the quantity
of silicon atom-bonded hydrogen atoms within this silicone rubber
composition relative to each 1 mol of silicon atom-bonded alkenyl
groups within the silicone rubber composition is no greater than
0.9 mols, and is even more preferably within a range from 0.5 to
0.9 mols, and most preferably from 0.6 to 0.8 mols.
[0047] The organohydrogenpolysiloxane of this component may use
either a single material, or a combination of two or more different
materials.
[0048] (C) Hydrosilylation Reaction Catalyst
[0049] The hydrosilylation reaction catalyst that represents the
component (C) promotes the hydrosilylation reaction between the
silicon atom-bonded alkenyl groups within the component (A1) and
the silicon atom-bonded hydrogen atoms within the component (B1).
There are no particular restrictions on this hydrosilylation
reaction catalyst, and all conventionally known substances can be
used, including platinum-based catalysts such as platinum black,
platinic chloride, chloroplatinic acid, reaction products of
chloroplatinic acid and monovalent alcohols, complexes of
chloroplatinic acid and olefins, and platinum bis(acetoacetate); as
well as other platinum group metal-based catalysts such as
palladium-based catalysts and rhodium-based catalysts, although
because they are used in the production of sealed LEDs within the
electronics field, catalysts that have been modified using
divinyltetramethyldisiloxane or divinyldiphenyldimethyldisiloxane
or the like, and contain no chlorine component, are preferred.
These hydrosilylation reaction catalysts may use either a single
material, or a combination of two or more different materials.
[0050] The blend quantity of the component (C) need only be an
effective catalytic quantity, and in this silicone rubber
composition, from an economic viewpoint, a typical quantity,
calculated as the mass of the platinum-group metal element, is
normally no greater than 200 ppm, preferably within a range from
0.1 to 50 ppm, and most preferably from 0.5 to 20 ppm.
[0051] Other Components
[0052] The silicone rubber composition may also contain
straight-chain diorganopolysiloxanes or network-type
organopolysiloxanes that contain silicon atom-bonded alkenyl groups
or silicon atom-bonded hydrogen atoms other than the aforementioned
components (A1) and (B1), and/or unreactive straight-chain or
cyclic diorganopolysiloxanes, or silphenylene-based compounds or
the like, provided the addition of these other components does not
impair the effects of the present invention.
[0053] In addition, other components such as an adhesion improver
for improving adhesion, a reaction retarder for ensuring
satisfactory pot life, or an inorganic filler for improving the
strength of the cured product may also be added. Examples of
suitable adhesion improvers include siloxanes modified by an epoxy
group or alkoxysilyl group or the like. Examples of suitable
reaction retarders include tetramethyltetravinylcyclosiloxane,
acetylene alcohols such as 1-ethylnylcyclohexanol and
3,5-dimethyl-1-hexyn-3-ol, and triallyl isocyanurate, as well as
modified products thereof. Examples of suitable inorganic fillers
include fumed silica, crushed silica and silicone resins.
Furthermore, dyes, pigments and flame retardants can also be added.
These components may use either a single material, or a combination
of two or more different materials.
[0054] The liquid curable silicone rubber composition can be
prepared by stirring and mixing together the aforementioned
component (A1), the component (B1) and the component (C), together
with any other components, using normal methods. By curing the
silicone rubber composition, preferably at 15 to 150.degree. C., a
cured silicone rubber layer that coats the LED can be formed.
[0055] <Addition Curing-Type Liquid Curable Silicone Resin
Composition>
[0056] For the addition curing-type liquid curable silicone resin
composition, any silicone resin with a three-dimensional network
structure which exhibits a hardness following curing that is
sufficient for practical use at the time of assembly of the LED
(for example, a value of at least 30 on a Shore D hardness meter),
can be used. Specific examples of these resins include those
described below.
RESIN COMPOSITION EXAMPLE 1
[0057] A resin composition comprising:
(A2) 100 parts by mass of an organopolysiloxane with a viscosity of
at least 10 mPas at 23.degree. C., represented by the average
composition formula (3) shown below: R.sup.3.sub.dSiO.sub.(4-d)/2
(3) (wherein, each R.sup.3 represents, independently, an
unsubstituted or substituted monovalent hydrocarbon group or alkoxy
group, or a hydroxyl group, provided 5 to 50 mol % of all R.sup.3
groups represent alkenyl groups, and d represents a number that
satisfies 1.ltoreq.d.ltoreq.2), (B2) 2 to 100 parts by mass of an
organohydrogenpolysiloxane with a viscosity of no greater than
1,000 mPas at 23.degree. C., and containing at least two silicon
atom-bonded hydrogen atoms within each molecule, represented by the
average composition formula (4) below:
R.sup.4.sub.eH.sub.fSiO.sub.(4-e-f)/2 (4) (wherein, each R.sup.4
represents, independently, an unsubstituted or substituted
monovalent hydrocarbon group that contains no aliphatic unsaturated
bonds, e represents a number from 0.7 to 2.1, f represents a number
from 0.01 to 1.0, and e+f satisfies a range from 0.8 to 3), and (C)
an effective quantity of a hydrosilylation reaction catalyst.
[0058] (A2) Organopolysiloxane
[0059] The organopolysiloxane that represents the component (A2)
represents the principal component of the silicone resin layer, and
as described above, is represented by the formula (3) shown above,
although from the viewpoints of workability and the mechanical
properties, the viscosity at 23.degree. C. is at least 10 mPas, and
is preferably within a range from 600 mPas through to a solid. This
organopolysiloxane contains alkenyl groups within the molecule, and
preferably contains from 2 to 6 alkenyl groups within each
molecule. Within the organopolysiloxane molecule, these silicon
atom-bonded alkenyl groups may be found at the molecular chain
terminals, at non-terminal molecular chain positions, or at both of
these positions.
[0060] There are no particular restrictions on the structure of the
organohydrogenpolysiloxane of this component, and suitable
structures include, for example, straight-chain, branched-chain,
three-dimensional network, or cyclic structures, although a
three-dimensional network structure is preferred.
[0061] In the formula (3) above, d preferably represents a positive
number from 1 to 1.8.
[0062] The number of carbon atoms within an unsubstituted or
substituted monovalent hydrocarbon group represented by R.sup.3 is
typically from 1 to 12, and preferably from 1 to 9. Examples of
this monovalent hydrocarbon group include the unsubstituted and
substituted monovalent hydrocarbon groups listed above as examples
of the group R. Furthermore, the number of carbon atoms within an
unsubstituted or substituted alkoxy group represented by R.sup.3 is
typically from 1 to 4, and preferably from 1 to 2. Examples of this
alkoxy group include a methoxy group, ethoxy group, propoxy group,
isopropoxy group, butoxy group, isobutoxy group, or tert-butoxy
group. For the R.sup.3 group, a methyl group, phenyl group, vinyl
group, norbornyl group, or isonorbornyl group is preferred.
[0063] In the formula (3) above, from the viewpoints of
availability and balancing the physical properties such as the
mechanical strength, it is preferable that all of the R.sup.3
groups other than the alkenyl groups represented by R.sup.3 are
methyl groups and/or phenyl groups.
[0064] Examples of the organopolysiloxane of this component
include:
[(C.sub.6H.sub.5)SiO.sub.3/2].sub.a[(CH.sub.3)(CH.sub.2.dbd.CH)SiO.sub.2/-
2].sub.b[(CH.sub.3).sub.2SiO.sub.2/2].sub.c
[(C.sub.6H.sub.5)SiO.sub.3/2].sub.a[(CH.sub.3).sub.2(CH.sub.2.dbd.CH)SiO.-
sub.1/2].sub.b[(CH.sub.3).sub.2SiO.sub.2/2].sub.c
[(C.sub.6H.sub.5)SiO.sub.3/2].sub.a[(CH.sub.3)(CH.sub.2.dbd.CH)SiO.sub.2/-
2].sub.b[(C.sub.6H.sub.5).sub.2SiO.sub.2/2].sub.c
[0065] (wherein, a, b and c each independently represent positive
numbers less than 1, and a+b+c=1).
[0066] The organopolysiloxane of this component may use either a
single material, or a combination of two or more different
materials.
[0067] (B2) Organohydrogenpolysiloxane
[0068] The organohydrogenpolysiloxane that represents the component
(B2) acts as a curing agent for curing the silicone resin
composition by forming a cross-linked structures with the component
(A2), and also acts as a reaction retarder that liquidizes the
component (A2) by dissolution, and is represented by the formula
(4) shown above. The viscosity of this organohydrogenpolysiloxane
at 23.degree. C. is no greater than 1,000 mPas, and from the
viewpoint of ensuring favorable workability, is preferably no
greater than 500 mPas, and is most preferably within a range from 1
to 300 mPas. This organohydrogenpolysiloxane must contain at least
two silicon atom-bonded hydrogen atoms within each molecule, and
preferably contains from 2 to 100, and most preferably from 3 to 50
of these hydrogen atoms. Within the organohydrogenpolysiloxane
molecule, these silicon atom-bonded hydrogen atoms may be found at
the molecular chain terminals, at non-terminal molecular chain
positions, or at both of these positions.
[0069] There are no particular restrictions on the structure of the
organohydrogenpolysiloxane of this component, and suitable
structures include, for example, straight-chain, branched-chain,
three-dimensional network, or cyclic structures, although
straight-chain and cyclic structures are preferred.
[0070] This component has the effect of improving adhesion by
penetrating the aforementioned cured silicone rubber layer during
curing of the silicone resin composition, and reacting with the
alkenyl groups, such as vinyl groups, within the cured silicone
rubber layer. For this reason, it is preferable to use a low
molecular weight compound that easily penetrates the cured silicone
rubber layer as a portion of this component (B2).
[0071] In the formula (4) above, e preferably represents a number
from 1.0 to 2.1, f preferably represents a number from 0.1 to 1.0,
and e+f preferably satisfies a range from 1.1 to 2.6.
[0072] Furthermore, the unsubstituted or substituted monovalent
hydrocarbon group that contains no aliphatic unsaturated bonds
represented by R.sup.4 typically contains from 1 to 12, and
preferably from 1 to 9, carbon atoms. Examples of this monovalent
hydrocarbon group include the monovalent hydrocarbon groups listed
above for the group R.sup.1.
[0073] Examples of the organohydrogenpolysiloxane of this component
include the same substances presented as specific examples of the
organohydrogenpolysiloxane of the component (B1) in the above.
[0074] The organohydrogenpolysiloxane of this component may use
either a single material, or a combination of two or more different
materials.
[0075] As described below, this silicone resin composition may also
include components containing silicon atom-bonded alkenyl groups
other than the component (A2), and/or components containing silicon
atom-bonded hydrogen atoms other than the component (B2).
Accordingly, the quantity of silicon atom-bonded hydrogen atoms in
this silicone resin composition relative to each 1 mol of silicon
atom-bonded alkenyl groups in this silicone resin composition is
typically within a range from 0.5 to 5 mols, and preferably within
a range from 0.6 to 3 mols. Moreover, the proportion of the total
number of silicon atom-bonded alkenyl groups in this silicone resin
composition accounted for by the silicon atom-bonded alkenyl groups
within the component (A2) is typically within a range from 70 to
100 mol %, and is preferably from 80 to 100 mol %. With such
values, a cured resin layer with excellent physical properties,
such as mechanical strength, can be obtained.
[0076] Furthermore, as was mentioned above, from the viewpoint of
improving the adhesion between the cured silicone rubber layer and
the cured silicone resin layer, it is preferable that the quantity
of silicon atom-bonded hydrogen atoms within this silicone resin
composition relative to each 1 mol of silicon atom-bonded alkenyl
groups within the silicone resin composition exceeds 0.9 mols, and
is even more preferably greater than 0.9 mols but no more than 3
mols, and most preferably greater than 0.9 mols but no more than 2
mols.
[0077] (C) Hydrosilylation Reaction Catalyst
[0078] The hydrosilylation reaction catalyst that represents the
component (C) is as described above in relation to the addition
curing-type liquid silicone rubber composition above, and the same
materials can be used.
[0079] The blend quantity of the component (C) need only be an
effective catalytic quantity, and in this composition, from an
economic viewpoint, a typical quantity, calculated as the mass of
the platinum-group metal element, is normally within a range from
0.1 to 200 ppm, and preferably from 2 to 50 ppm, and most
preferably from 3 to 20 ppm.
[0080] Other Components
[0081] The silicone resin composition may also contain, in addition
to the components (A2), (B2) and (C), adhesion improvers, reaction
retarders, and inorganic fillers and the like, provided the
addition of these other components does not impair the effects of
the present invention. Specific examples of these other components
include the materials listed above in the paragraph concerning
other components of the silicone rubber composition.
[0082] Production Method
[0083] A liquid curable silicone resin composition 1 can be
prepared by stirring and mixing together the aforementioned
component (A2), the component (B2) and the component (C), together
with any other components, using normal methods. By curing the
silicone resin composition, preferably at 80 to 150.degree. C., a
cured silicone resin layer that can be used in a silicone-sealed
LED of the present invention can be produced.
RESIN COMPOSITION EXAMPLE 2
[0084] A resin composition comprising:
(A3) a siloxane-based compound that contains at least two silicon
atom-bonded alkenyl groups within each molecule,
[0085] (B3) a siloxane-polycyclic hydrocarbon-based compound, which
is an addition reaction product of (a) a siloxane-based compound
containing at least three silicon atom-bonded hydrogen atoms within
each molecule, and (b) a polycyclic hydrocarbon containing two
addition reactive carbon-carbon double bonds within each molecule,
and contains at least two silicon atom-bonded hydrogen atoms within
each molecule, and
(C) a hydrosilylation reaction catalyst.
[0086] (A3) Siloxane-Based Compound
[0087] The siloxane-based compound that represents the component
(A3) is a siloxane-based compound that contains at least two
silicon atom-bonded alkenyl groups within each molecule, and
undergoes an addition to the component (B3) described below via a
hydrosilylation reaction to yield the cured product. Within the
siloxane-based compound molecule, these silicon atom-bonded alkenyl
groups may be found at the molecular chain terminals, at
non-terminal molecular chain positions, or at both of these
positions.
[0088] Examples of this component (A3) include the cyclic siloxane
compounds represented by the general formula (5) shown below:
##STR1## (wherein, each R.sup.5 represents, independently, an
unsubstituted or substituted monovalent hydrocarbon group of 1 to
12, and preferably 1 to 6, carbon atoms, although of the plurality
of R.sup.5 groups, at least two are alkenyl groups, and p
represents an integer from 3 to 20, preferably from 3 to 8), and
linear siloxane-based compounds represented by the general formula
(6) shown below:
R.sup.6.sub.3SiO--(R.sup.5.sub.2SiO).sub.q--SiR.sup.6.sub.3 (6)
(wherein, each R.sup.5 and R.sup.6 represents, independently, an
unsubstituted or substituted monovalent hydrocarbon group of 1 to
12, and preferably 1 to 6, carbon atoms, although of the plurality
of R.sup.5 and/or R.sup.6 groups, at least two are alkenyl groups,
and in a case where all of the R.sup.5 groups are not alkenyl
groups, q represents either 0, or an integer from 1 to 100, and
preferably from 1 to 20, and in a case where all of the R.sup.6
groups are not alkenyl groups, or only one is an alkenyl group, q
represents an integer from 2 to 100, and preferably from 2 to
20).
[0089] Examples of R.sup.5 and R.sup.6 include alkyl groups such as
a methyl group, ethyl group, propyl group, isopropyl group, butyl
group, tert-butyl group, pentyl group, hexyl group, heptyl group,
octyl group, nonyl group, decyl group, or octadecyl group;
cycloalkyl groups such as a cyclopentyl group or cyclohexyl group;
aryl groups such as a phenyl group, tolyl group, xylyl group, or
naphthyl group; aralkyl groups such as a benzyl group, phenethyl
group, or 3-phenylpropyl group; halogenated alkyl groups such as a
3,3,3-trifluoropropyl group or 3-chloropropyl group; and alkenyl
groups such as a vinyl group, allyl group, butenyl group, pentenyl
group or hexenyl group.
[0090] Amongst these, from the viewpoint of industrial
availability, in those cases where R.sup.5 and R.sup.6 are alkenyl
groups, vinyl groups are preferred, whereas in those cases where
they are not alkenyl groups, methyl groups are preferred.
[0091] Specific examples of suitable compounds for the component
(A3) are shown below, although the component (A3) is in no way
restricted by these examples. (ViMeSiO).sub.3 (ViMeSiO).sub.4
(ViMeSiO).sub.3(Me.sub.2SiO) (ViMeSiO).sub.4(Me.sub.2SiO)
Me.sub.3SiO-(ViMeSiO).sub.5(Me.sub.2SiO).sub.5--SiMe.sub.3
ViMe.sub.2SiO-(Me.sub.2SiO).sub.5--SiMe.sub.2Vi
ViMe.sub.2SiO-(Ph.sub.2SiO).sub.5(Me.sub.2SiO).sub.5--SiMe.sub.2Vi
ViMe.sub.2SiO-(ViMeSiO).sub.5(Me.sub.2SiO).sub.5--SiMe.sub.2Vi
[0092] The component (A3) may use either a single material, or a
combination of two or more different materials.
[0093] (B3) Siloxane-Polycyclic Hydrocarbon-Based Compound
[0094] The siloxane-polycyclic hydrocarbon-based compound of the
component (B3) contains at least two silicon atom-bonded hydrogen
atoms within each molecule, and is a hydrocarbon-based compound
that contains both a siloxane structure and a polycyclic structure.
This siloxane-polycyclic hydrocarbon-based compound is an addition
reaction product of (a) a siloxane-based compound containing at
least three silicon atom-bonded hydrogen atoms within each
molecule, and (b) a polycyclic hydrocarbon containing two addition
reactive carbon-carbon double bonds within each molecule.
[0095] The siloxane-polycyclic hydrocarbon-based compound of this
component preferably contains from 2 to 100, and even more
preferably from 2 to 50, silicon atom-bonded hydrogen atoms within
each molecule. Within the siloxane-polycyclic hydrocarbon-based
compound molecule, these silicon atom-bonded hydrogen atoms may be
found at the molecular chain terminals, at non-terminal molecular
chain positions, or at both of these positions. Furthermore, the
siloxane-based compound (a) preferably contains from 3 to 10, and
even more preferably from 3 to 5, silicon atom-bonded hydrogen
atoms within each molecule.
[0096] -Component (a)-
[0097] Examples of the siloxane-based compound containing at least
three silicon atom-bonded hydrogen atoms within each molecule (a),
which is a reaction raw material for the component (B3), include
cyclic siloxane-based compounds represented by the general formula
(7): ##STR2## (wherein, each R.sup.7, R.sup.8 and R.sup.9
represents, independently, a hydrogen atom or an unsubstituted or
substituted monovalent hydrocarbon group of 1 to 12, and preferably
1 to 6, carbon atoms, r represents an integer from 3 to 10, and
preferably from 3 to 8, s represents an integer from 0 to 7, and
preferably from 0 to 2, and r+s is an integer from 3 to 10, and
preferably from 3 to 6), and linear siloxane-based compounds
represented by the general formula (8) shown below:
R.sup.7.sub.3SiO--(HR.sup.7SiO).sub.t(R.sup.8R.sup.9SiO).sub.u--S-
iR.sup.7.sub.3 (8) (wherein, each R.sup.7, R.sup.8 and R.sup.9 is
as defined above for the general formula (7), t represents an
integer from 3 to 50, and preferably from 3 to 30, u represents an
integer from 0 to 47, and preferably from 0 to 20, and t+u is an
integer from 3 to 50, and preferably 3 to 30).
[0098] In those cases where R.sup.7, R.sup.8 and R.sup.9 represent
monovalent hydrocarbon groups, specific examples of the groups
include alkyl groups such as a methyl group, ethyl group, propyl
group, isopropyl group, butyl group, tert-butyl group, pentyl
group, isopentyl group, hexyl group, or sec-hexyl group; cycloalkyl
groups such as a cyclopentyl group or cyclohexyl group; aryl groups
such as a phenyl group, or o-, m-, or p-tolyl group; aralkyl groups
such as a benzyl group or 2-phenylethyl group; alkenyl groups such
as a vinyl group, allyl group, 1-butenyl group, or 1-hexenyl group;
alkenylaryl groups such as a p-vinyl-phenyl group; and groups in
which one or more of the hydrogen atoms within these groups have
been substituted with a halogen atom, cyano group, or epoxy group,
including halogenated alkyl groups such as a chloromethyl group,
3-chloropropyl group, or 3,3,3-trifluoropropyl group, as well as a
2-cyanoethyl group or a 3-glycidoxypropyl group. Amongst these,
groups other than alkenyl groups and alkenylaryl groups are
preferred, and cases in which all the groups are methyl groups are
particularly desirable.
[0099] Specific examples of suitable compounds for the component
(a) are shown below, although the component (a) is in no way
restricted by these examples. (HMeSiO).sub.3 (HMeSiO).sub.4
(HMeSiO).sub.3(Me.sub.2SiO) (HMeSiO).sub.4(Me.sub.2SiO)
Me.sub.3SiO-(HMeSiO).sub.5(Me.sub.2SiO).sub.5--SiMe.sub.3
Me.sub.3SiO--(HMeSiO).sub.20(Me.sub.2SiO).sub.20--SiMe.sub.3
[0100] The component (a) may use either a single material, or a
combination of two or more different materials.
[0101] -Component (b)-
[0102] In the polycyclic hydrocarbon containing two addition
reactive carbon-carbon double bonds within each molecule (b), which
is the other reaction raw material for the component (B3), the term
"addition reactive" refers to an ability to accept addition of
silicon atom-bonded hydrogen atoms (known as a hydrosilylation
reaction).
[0103] Examples of the polycyclic hydrocarbon of the component (b)
include, for example, (i) compounds in which addition reactive
carbon-carbon double bonds have been formed between sets of
adjacent carbon atoms amongst the carbon atoms that form the
polycyclic skeleton of the polycyclic hydrocarbon, (ii) compounds
in which hydrogen atoms bonded to the carbon atoms that form the
polycyclic skeleton of the polycyclic hydrocarbon have been
substituted with addition reactive carbon-carbon double
bond-containing groups, (iii) compounds in which an addition
reactive carbon-carbon double bond has been formed between two
adjacent carbon atoms amongst the carbon atoms that form the
polycyclic skeleton of the polycyclic hydrocarbon, and a hydrogen
atom bonded to a carbon atom that forms the polycyclic skeleton of
the polycyclic hydrocarbon has been substituted with an addition
reactive carbon-carbon double bond-containing group.
[0104] There are no particular restrictions on the
siloxane-polycyclic hydrocarbon-based compound, provided the above
requirements are fulfilled, although compounds represented by a
general formula (9) shown below: H--X--(Y--X).sub.v--Y' (9)
[0105] (wherein, X represents a bivalent residue of the above
siloxane-based compound (a), Y represents a bivalent residue of the
above polycyclic hydrocarbon (b), Y' represents a monovalent
residue of the above polycyclic hydrocarbon (b), H represents a
hydrogen atom, and v represents an integer from 0 to 1,000, and
preferably from 0 to 100),
[0106] compounds represented by a general formula (10) shown below:
H--X--(Y--X).sub.w--H (10)
[0107] (wherein, X, Y and H are as defined above, and w represents
an integer from 1 to 1,000, and preferably from 1 to 100),
[0108] and compounds represented by a general formula (11) shown
below: Y'--X--(Y--X).sub.z--Y' (11)
[0109] (wherein, X, Y and Y' are as defined above, and z represents
an integer from 1 to 1,000, and preferably from 1 to 100), are
preferred.
[0110] Examples of the group X (in other words, the bivalent
residue of the above siloxane-based compound (a)) in the above
formulas (9) to (11) include, for example, cyclic or chain-like
bivalent groups represented by the general formula shown below:
##STR3##
[0111] (wherein, each R.sup.10 represents, independently, a
monovalent hydrocarbon group or alkoxy group of 1 to 12, and
preferably 1 to 6, carbon atoms, and x represents an integer of at
least 1, and preferably 2 or greater, and most preferably 2).
[0112] Examples of the monovalent hydrocarbon group represented by
R.sup.10 include alkyl groups such as a methyl group, ethyl group,
propyl group, isopropyl group, butyl group, tert-butyl group, or
n-hexyl group; and aryl groups such as a phenyl group. Furthermore,
examples of the alkoxy group represented by R.sup.10 include a
methoxy group, ethoxy group or propoxy group.
[0113] Specific examples of X include, for example, the cyclic
siloxane residues shown below: ##STR4## and the chain-like siloxane
residues shown below: ##STR5##
[0114] Specific examples of the group Y in the above formulas, that
is, the bivalent residue of the polycyclic hydrocarbon of the above
component (b), include the bivalent residues specifically
represented by the structural formulas shown below: ##STR6##
[0115] In the case of asymmetric bivalent residues represented by
the above structural formulas, the left-right direction of the
residue is not restricted to the orientation shown in the formula,
and each of the structural formulas also includes the structure
produced by a 180 degree rotation within the plane of the
paper.
[0116] Specific examples of the group Y' in the above formulas,
that is, the monovalent residue of the polycyclic hydrocarbon of
the above component (b), include the residues represented by the
structural formulas shown below: ##STR7##
[0117] Next, specific examples of preferred forms of the
aforementioned component (B3) are shown below, although the
component (B3) is in no way restricted by these examples. ##STR8##
(In the formulas above, w is as defined above for the formula
(10))
[0118] This component (B3), that is to say, the reaction product of
(a) a siloxane-based compound containing at least three silicon
atom-bonded hydrogen atoms within each molecule, and (b) a
polycyclic hydrocarbon containing two addition reactive
carbon-carbon double bonds within each molecule, which is a
siloxane-polycyclic hydrocarbon-based compound containing at least
two silicon atom-bonded hydrogen atoms within each molecule, is
prepared, for example, by an addition reaction between cyclic
1,3,5,7-tetramethylcyclotetrasiloxane as the component (a), and
5-vinylbicyclo[2.2.1]hept-2-ene, represented by the structural
formula (12) shown below: ##STR9## 6-vinylbicyclo[2.2.1]hept-2-ene,
represented by the structural formula (13) shown below: ##STR10##
or a combination of the above two compounds (hereafter, these cases
are not differentiated, and are referred to simply as
"vinylnorbornene"), or a dicyclopentadiene represented by the
structural formula (14) shown below: ##STR11## as the composition
(b), in the presence of a hydrosilylation reaction catalyst (C)
such as platinum described below.
[0119] The substitution position of the vinyl group of the above
vinylnorbornenes may result in either the endo-form or the
exo-form, or may also yield a combination of both isomers.
[0120] At the time of the above addition reaction, the quantities
used of the component (a) and the component (b) are adjusted so
that the quantity used of the component (a) such as
1,3,5,7-tetramethylcyclotetrasiloxane, relative to each 1 mol of
the component (b) such as dicyclopentadiene, is within a range from
0.5 to 2 mols, and preferably from 1 to 1.5 mols, and most
preferably from 1.1 to 1.3 mols, thereby enabling a
siloxane-polycyclic hydrocarbon-based compound that contains at
least two SiH groups within each molecule to be prepared as the
component (B3).
[0121] The siloxane-polycyclic hydrocarbon-based compound of the
component (B3) may use either a single material, or a combination
of two or more different materials.
[0122] As is described below, this silicone resin composition may
also include components containing silicon atom-bonded alkenyl
groups other than the component (A3), and/or components containing
silicon atom-bonded hydrogen atoms other than the component (B3).
Accordingly, the quantity of silicon atom-bonded hydrogen atoms in
this silicone resin composition relative to each 1 mol of silicon
atom-bonded alkenyl groups in this silicone resin composition is
typically within a range from 0.3 to 3.0 mols, and preferably from
0.8 to 2.0 mols. Moreover, the proportion of the total number of
silicon atom-bonded alkenyl groups in this silicone resin
composition accounted for by the silicon atom-bonded alkenyl groups
in the component (A3) is typically within a range from 20 to 100
mol %, and is preferably from 40 to 100 mol %. With such values, a
cured silicone resin layer with excellent physical properties, such
as mechanical strength, can be obtained.
[0123] Furthermore, as mentioned above, from the point of improving
the adhesion between the cured silicone rubber layer and the cured
silicon resin layer, it is preferable that the quantity of silicon
atom-bonded hydrogen atoms within this silicone resin composition,
relative to each 1 mol of silicon atom-bonded alkenyl groups in
this silicon resin composition, exceeds 0.9 mol, and is even more
preferably greater than 0.9 mols but no more than 3.0 mols, and
most preferably greater than 0.9 mols but no more than 2.0
mols.
[0124] (C) Hydrosilylation Reaction Catalyst
[0125] The hydrosilylation reaction catalyst that represents the
component (C) is as described above, and the same compounds can be
used as suitable examples.
[0126] There are no particular restrictions on the blend quantity
of the component (C), which need only be an effective catalytic
quantity, although in this silicone resin composition, a typical
quantity, calculated as the mass of the platinum-group metal
element, is normally within a range from 1 to 500 ppm, and
preferably from 2 to 100 ppm. By using a blend quantity that falls
within this particular range, the time required for the curing
reaction of the silicone resin composition is appropriate, and
problems such as coloring of the cured product do not occur.
[0127] The hydrosilylation reaction catalyst of this component may
use either a single material, or a combination of two or more
different materials.
[0128] Other Components
[0129] The silicone resin composition may also contain, in addition
to the components (A3), (B3) and (C), adhesion imparting agents,
reaction retarders, and inorganic fillers and the like, provided
the addition of these other components does not impair the effects
of the present invention. Specific examples of these other
components include the materials listed above in the paragraph
concerning other components of the silicone rubber composition.
[0130] In addition, an antioxidant can also be added if required.
Any conventionally known antioxidant can be used. Examples of
suitable materials include 2,6-di-t-butyl-4-methylphenol,
2,5-di-t-amylhydroquinone, 2,5-di-t-butylhydroquinone,
4,4'-butylidenebis(3-methyl-6-t-butylphenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol), and
2,2'-methylenebis(4-ethyl-6-t-butylphenol).
[0131] In those cases where an antioxidant is used, there are no
particular restrictions on the blend quantity used provided it is
an effective quantity as an antioxidant, although a typical
quantity, calculated relative to the combined mass of the component
(A3) and the component (B3), is normally within a range from 10 to
10,000 ppm, and preferably from 100 to 1,000 ppm. By ensuring the
blend quantity falls within this particular range, the
antioxidation action can be manifested satisfactorily, and a cured
silicone resin layer with excellent optical characteristics, in
which coloring, turbidity, or oxidative degradation do not occur,
can be obtained.
[0132] In addition, light stabilizers can also be added for
imparting resistance to light deterioration caused by light energy
from sunlight or fluorescent lights or the like. Hindered amine
based stabilizers, which capture the radicals generated upon
oxidation and deterioration of the cured product caused by light
exposure, are ideal as these light stabilizers, and by using such
light stabilizers in combination with the antioxidants described
above, the oxidation prevention effect can be further improved.
Specific examples of these light stabilizers include
bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate and
4-benzoyl-2,2,6,6-tetramethylpiperidine.
[0133] Furthermore, in order to regulate the viscosity of the
silicone resin composition, or regulate the hardness of the cured
silicone resin layer, straight-chain diorganopolysiloxanes or
network-type organopolysiloxanes containing either silicon
atom-bonded alkenyl groups or silicon atom-bonded hydrogen atoms,
and/or unreactive straight-chain or cyclic diorganopolysiloxanes or
silphenylene-based compounds may also be added.
[0134] These other components may use either a single material, or
a combination of two or more different materials.
[0135] A liquid curable type silicone resin composition 2 can be
prepared by stirring and mixing together the component (A3), the
component (B3) and the component (C), together with any other
components, using conventional methods. By curing this composition,
preferably at 60 to 180.degree. C. over a period of 5 to 180 hours,
a cured silicone resin layer used in a silicone-sealed LED of the
present invention can be produced.
[0136] <Production Process for Silicone-Sealed LED>
[0137] The silicone-sealed LED of the present invention can be
produced by the process comprising the steps of:
[0138] (1) coating a LED chip with a cured silicone rubber layer,
and
[0139] (2) coating and sealing a periphery of the cured silicone
rubber layer with a cured silicone resin layer. The cured silicone
rubber layer is preferably a cured product of a liquid curable
silicone rubber composition, and the cured silicone resin layer is
preferably a cured product of a liquid curable silicone resin
composition. The step (1) comprises the steps of:
[0140] applying the liquid curable silicone rubber composition to
the LED chip and
[0141] curing the liquid curable silicone rubber composition to
form the cured silicone rubber layer on the LED chip. The step (2)
comprises the steps of:
[0142] applying the liquid curable silicone resin composition to
the periphery of the cured silicone rubber layer and
[0143] curing the liquid curable silicone resin composition to form
the cured silicone resin layer on the periphery of the cured
silicone rubber layer. The liquid curable silicone rubber
composition is as described above, and the same compositions can be
used as suitable examples. The liquid curable silicone resin
composition is also as described above, and the same compositions
can be used as suitable examples.
[0144] <Sealing Process for LED>
[0145] A LED can be sealed by the process comprising the steps
of:
[0146] (3) coating a LED chip with a cured silicone rubber layer,
and
[0147] (4) coating and sealing a periphery of the cured silicone
rubber layer with a cured silicone resin layer. The cured silicone
rubber layer is preferably a cured product of a liquid curable
silicone rubber composition, and the cured silicone resin layer is
preferably a cured product of a liquid curable silicone resin
composition. The step (3) comprises the steps of:
[0148] applying the liquid curable silicone rubber composition to
the LED chip and
[0149] curing the liquid curable silicone rubber composition to
form the cured silicone rubber layer on the LED chip. The step (4)
comprises the steps of:
[0150] applying the liquid curable silicone resin composition to
the periphery of the cured silicone rubber layer and
[0151] curing the liquid curable silicone resin composition to form
the cured silicone resin layer on the periphery of the cured
silicone rubber layer. The liquid curable silicone rubber
composition is as described above, and the same compositions can be
used as suitable examples. The liquid curable silicone resin
composition is also as described above, and the same compositions
can be used as suitable examples.
EXAMPLES
[0152] As follows is a more detailed description of the present
invention using a series of examples, although the present
invention is in no way limited by these examples.
Rubber Synthesis Example 1
[0153] A silicone rubber composition 1 was prepared by uniformly
mixing 100 parts by mass of a dimethylpolysiloxane with both
molecular chain terminals blocked with vinyl groups and with a
viscosity of 600 mPas at 23.degree. C., a quantity of a platinum
catalyst with divinyltetramethyldisiloxane ligands equivalent to a
mass of platinum of 10 ppm, 0.1 parts by mass of
tetramethyltetravinyltetrasiloxane, and 0.6 parts by mass of a
compound represented by a formula:
Me.sub.3SiO(SiMe(H)O).sub.11SiMe.sub.3. In this silicone rubber
composition 1, the quantity of silicon atom-bonded hydrogen atoms
relative to each 1 mol of silicon atom-bonded vinyl groups, is 0.54
mols. This silicone rubber composition 1 was cured by heating for
one hour at 120.degree. C., thereby yielding a cured silicone
rubber 1. The penetrability of the cured silicone rubber 1 was 15,
and the hardness, measured using a JIS Type A hardness meter, was
0.
Rubber Synthesis Example 2
[0154] With the exceptions of altering the blend quantity of the
compound represented by the formula:
Me.sub.3SiO(SiMe(H)O).sub.11SiMe.sub.3 from the 0.6 parts by mass
used in the silicone rubber composition 1 to 0.3 parts by mass, and
also adding 2 parts by mass of a compound represented by a formula:
Me.sub.3SiO(SiMeHO).sub.2(SiMe.sub.2O).sub.7(SiMe(CH.sub.2CH.sub.2Si(OMe)-
.sub.3O)SiMe.sub.3, a silicone rubber composition 2 was prepared in
the same manner as the rubber synthesis example 1, thereby yielding
a cured silicone rubber composition 2. In the silicone rubber
composition 2, the quantity of silicon atom-bonded hydrogen atoms
relative to each 1 mol of silicon atom-bonded vinyl groups, is 0.64
mols. The penetrability of the cured silicone rubber 2 was 23, and
the hardness, measured using a JIS Type A hardness meter, was
0.
Rubber Synthesis Example 3
[0155] A silicone rubber composition 3 was prepared by uniformly
mixing 100 parts by mass of a methylphenylpolysiloxane with both
molecular chain terminals blocked with vinyl groups, with a
viscosity of 4,000 mPas at 23.degree. C., and containing 30 mol %
of phenyl groups at non-terminal molecular chain positions, a
quantity of a platinum catalyst with divinyltetramethyldisiloxane
ligands equivalent to a mass of platinum of 10 ppm, 0.1 parts by
mass of tetramethyltetravinyltetrasiloxane, 0.5 parts by mass of a
compound represented by a formula:
Me.sub.3SiO(SiMe(H)O).sub.11(iMe.sub.3, and 2 parts by mass of a
compound represented by a formula:
Me.sub.3SiO(SiMeHO).sub.2(SiMe.sub.2O).sub.7(SiMe(CH.sub.2CH.sub.2Si(OMe)-
.sub.3O)SiMe.sub.3. In the silicone rubber composition 3, the
quantity of silicon atom-bonded hydrogen atoms relative to each 1
mol of silicon atom-bonded vinyl groups, is 0.63 mols. This
silicone rubber composition 3 was cured by heating for one hour at
120.degree. C., thereby yielding a cured silicone rubber 3. The
penetrability of the cured silicone rubber 3 was 17, and the
hardness, measured using a JIS Type A hardness meter, was 0.
Resin Synthesis Example 1
[0156] 116 parts by mass of phenyltrichlorosilane, 28.2 parts by
mass of vinylmethyldichlorosilane, and 32.3 parts by mass of
dimethyldichlorosilane were placed in a dropping funnel, and added
dropwise to a flask charged with 324 parts by mass of toluene and
304 parts by mass of water, and cohydrolysis and a subsequent
condensation polymerization reaction yielded a siloxane compound
represented by a formula:
(CH.sub.3).sub.0.7(C.sub.6H.sub.5).sub.0.55(CH.sub.2.dbd.CH).sub-
.0.20SiO.sub.1.28, which after 30 minutes at 150.degree. C. existed
as a toluene solution with a non-volatile fraction of 50% by mass.
To 100 parts by mass of the siloxane compound within this solution
were added 25 parts by mass of a cross-linking agent represented by
an average formula shown below, which has a viscosity of 2 mPas at
23.degree. C., contains 15 mols of phenyl groups, and generates 200
ml of hydrogen gas, ##STR12##
[0157] and 10 parts by mass of an adhesive imparting agent
represented by a structural formula shown below, ##STR13## and
following stirring for one hour at 80.degree. C., the mixture was
heated to 120.degree. C. and the toluene was removed under reduced
pressure, yielding a uniform, colorless and transparent liquid. To
this liquid was added a quantity of a platinum catalyst with
divinyltetramethyldisiloxane ligands equivalent to a mass of
platinum of 10 ppm, and after uniform mixing, the composition was
heated and cured at 100.degree. C. for one hour, and then at
150.degree. C. for a further one hour, thereby yielding a colorless
and transparent cured silicone resin composition 1. The hardness of
this cured silicone resin composition 1, measured using a Shore D
hardness meter, was 68. In this silicone resin composition 1, the
quantity of silicon atom-bonded hydrogen atoms relative to each 1
mol of silicon atom-bonded vinyl groups, is 1.05.
Resin Synthesis Example 2
[0158] 150 parts by mass of a silicone resin composition comprising
Me.sub.3SiO.sub.1/2 units, ViMe.sub.2SiO.sub.1/2 units, and
SiO.sub.4/2 units, in which the ratio of the combined quantity of
the Me.sub.3SiO.sub.1/2 units and the ViMe.sub.2SiO.sub.1/2 units
relative to the SiO.sub.4/2 units is a molar ratio of 0.95, was
dissolved in toluene, yielding a 50% by mass toluene solution.
After stripping of the toluene solution for one hour under
conditions of 120.degree. C. and 15 mmHg, the quantity of vinyl
groups within the silicone resin composition was, 0.08 mols per 100
g of the remaining solid fraction. To the aforementioned toluene
solution were added 25 parts by mass of a dimethylsilicone polymer
with both molecular chain terminals blocked with vinyl groups and
with a viscosity of 60 mPas at 23.degree. C., 3 parts by mass of
tetramethyltetravinyltetrasiloxane, 10 parts by mass of a compound
represented by a formula: Me.sub.3SiO(SiMeHO).sub.11SiMe.sub.3, and
5 parts by mass of an adhesive imparting agent represented by a
structural formula shown below: ##STR14## following stirring to
generate a uniform solution, stripping was conducted under
conditions of 120.degree. C. and 15 mmHg, yielding a transparent
liquid. To this liquid was added a quantity of a platinum catalyst
with divinyltetramethyldisiloxane ligands equivalent to a mass of
platinum of 10 ppm, and after uniform mixing, the composition was
heated and cured at 100.degree. C. for one hour, and then at
150.degree. C. for a further one hour, thereby yielding a colorless
and transparent cured silicone resin composition 2. The hardness of
this cured silicone resin composition 2, measured using a Shore D
hardness meter, was 48. In this silicone resin composition 2, the
quantity of silicon atom-bonded hydrogen atoms relative to the
silicon atom-bonded vinyl groups, is 1.43.
Resin Synthesis Example 3
[0159] A 500 mL four-neck flask fitted with a stirrer, a condenser
tube, a dropping funnel, and a thermometer was charged with 80 g of
toluene and 115.2 g (0.48 mols) of
1,3,5,7-tetramethylcyclotetrasiloxane, and the flask was then
heated to 117.degree. C. using an oil bath. 0.05 g of carbon powder
supporting 5% by mass of a platinum metal was then added to the
solution, and with the mixture undergoing constant stirring, 48 g
(0.4 mols) of vinylnorbornene (product name: V0062, manufactured by
Tokyo Kasei Kogyo Co., Ltd., an approximately equimolar isomeric
mixture of 5-vinylbicyclo[2.2.1]hept-2-ene and
6-vinylbicyclo[2.2.1]hept-2-ene) was added dropwise over a period
of 16 minutes. Following completion of the dropwise addition, the
reaction mixture was stirred for a further 16 hours while heating
at 125.degree. C., and was then cooled to room temperature
(25.degree. C.). Subsequently, the platinum metal-supporting carbon
was removed by filtration, and the toluene was removed under
reduced pressure, yielding a colorless and transparent oily
reaction product (viscosity at 23.degree. C.: 2,500 mPas). 68 parts
by mass of this reaction product (A3), 32 parts by mass of
(ViMeSiO).sub.4 (B3), a platinum-vinylsiloxane complex in
sufficient quantity to provide 20 ppm of platinum relative to the
combined mass of the component (A3) and the component (B3), and
0.03 parts by mass of 1-ethynylcyclohexanol were mixed together
uniformly, yielding a silicone resin composition 3. This silicone
resin composition 3 was poured into a mold made from glass plates
such that it becomes to generate a thickness of 4 mm, and was then
heated at 150.degree. C. for 2 hours, thus yielding a cured
silicone resin 3. The hardness of this cured silicone resin
composition 3, measured using a Shore D hardness meter, was 54. In
this silicone resin composition 3, the quantity of silicon
atom-bonded hydrogen atoms relative to the silicon atom-bonded
vinyl groups, is 1.00.
EXAMPLES
[0160] -Adhesion Testing-
[0161] The adhesion of the cured silicone rubber layers and the
cured silicone resin layers obtained in the above synthesis
examples was tested in accordance with the following method.
[0162] Firstly, the prepared silicone rubber composition was poured
into a glass Petri dish of diameter 25 mm, the glass Petri dish
containing the silicone rubber composition was placed in a dryer,
and the silicone rubber composition was cured at 120.degree. C.
over a period of one hour. Following removal of the Petri dish from
the dryer and cooling to room temperature, the prepared silicone
resin composition was added dropwise onto the obtained cured
silicone rubber layer, and the silicone resin composition was cured
under the curing conditions (temperature and time) described in the
corresponding resin synthesis example or resin comparative
synthesis example described above. Following removal of the
obtained laminate of the cured silicone rubber layer and the cured
silicone resin layer from the glass Petri dish, the adhesion
between the cured silicone rubber layer and the cured silicone
resin layer was tested by grasping the layer of the cured silicone
resin by hand, and separating the two layers.
[0163] At the point of separation, if cohesive failure of the cured
silicone rubber layer occurred, the adhesion was evaluated as
favorable, indicated by an A. If the cured silicone rubber layer
and the cured silicone resin layer were strongly adhered, but
separation was achievable, the adhesion was evaluated as
satisfactory, indicated by a B. If separation occurred easily
between the cured silicone rubber layer and the silicone resin
layer, the adhesion was evaluated as poor, indicated by a C. The
obtained results are shown in Table 1. TABLE-US-00001 TABLE 1
Rubber 1 2 3 Resin 1 A A A 2 A A A 3 A A A
* * * * *